This invention relates generally to a sphere launching apparatus for launching a sphere in a fluid carrying pipeline. In particular, the invention relates to an apparatus for a sequentially ejecting spheres by gravity into a pipeline upon the opening and closing of a check valve.
Numerous apparatus have been proposed in the past which provide a means for ejecting plugs or spheres (commonly referred to as "pigs") into pipelines. Examples of such apparatus are exemplified in U.S. Pat. Nos.: 2,818,592, 2,965,125; 3,000,028; 3,028,996; 3,146,477; 3,166,094; 3,266,077; 3,322,140; 3,397,570; 3,408,674; and, 3,543,769.
In particular, U.S. Pat. No. 3,169,263 issued to H. N. Eagleton which is assigned to the same entity as this application, discloses a sphere launching apparatus which is operated upon the opening and closing of a check valve. This device discloses in FIG. 4 a releasing means 96 which is pivotally mounted about a pivot pin 94 and includes a roller 98 for engaging a clapper valve for operating the releasing means. A catcher means 100 is also pivotally mounted about the shaft 94 and as best shown in FIG. 3 of the Eagleton patent includes clutch shoulders 104 and 105 which alternately engage similar clutch shoulders 107 on the releasing means 96. The clutch shoulders provide a lost motion connector between the releasing means and catcher means so that the releasing means can be rotated independently of the catching means after the catching means has rotated a predetermined amount. As best shown in FIG. 4 of said patent, when the portion 109 has engaged the top of the valve, the catching means 100 can no longer rotate counterclockwise while the releasing means 96 can further rotate counterclockwise to allow the sphere 102(a) to be released.
In the case of very large pipelines which may be in the order of three feet in diameter, the spheres may become very heavy. It is best shown in FIG. 1 of the Eagleton patent, a plurality of spheres are provided for sequentially releasing upon actuation of the catcher means and releasing means. Accordingly, should the launcher tube 10 be of such a size to allow for very large spheres, the weight of these spheres would react through gravity on the catcher arm 100. After a sphere 102(a) is released, the clapper of the valve is closed which allows the releasing means 96 to rotate until the shoulder 107 engages the shoulder 105. At this point the releasing means will cause the catcher means to rotate clockwise as shown in FIG. 4 to allow the next sphere 102(b) to roll into engagement with the releasing means 96. If this sphere engages the releasing means before the clapper is closed, it will be necessary to exert sufficient force on the clapper which in turn exerts the force on the releasing means to force the sphere 102(b) and any additional spheres back up into the launching tube 10 to seal off the launching tube. When the launching tube is full of very large spheres, this may require a very large amount of force to close the clapper valve.
Also the shoulders 104, 105 and 107 of Eagleton control the angular relationship between the releasing means and catcher means. Accordingly, some care must be exercised in manufacturing regarding tolerances between the parts.
It is an object of this invention to provide a linkage mechanism which will not be actuated to release a sphere until the clapper is almost closed so that the clapper will be able to close or substantially close before the releasing means is engaged by the next sphere. It is also an object of this invention to provide a mechanism which can be manufactured simply and economically without the need for very close tolerances. It is also an object of the invention to provide an apparatus which can be adjusted and thus eliminate the need for very close tolerances. Other objects of the invention will be apparent from the following description.